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See detailSound production to electric discharge: sonic muscle evolution in progress in Synodontis spp. catfishes (Mochokidae)
Boyle, Kelly; Colleye, Orphal ULg; Parmentier, Eric ULg

in Proceedings of the Royal Society B : Biological Sciences (2014), 281

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See detailHearing capacities and otolith size in two ophidiiform species (Ophidion rochei and Carapus acus)
Kever, Loïc ULg; Colleye, Orphal ULg; Herrel, Anthony et al

in Journal of Experimental Biology (2014), 217

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See detailContribution to the study of acoustic communication in two Belgian river bullheads (Cottus rhenanus and C. perifretum) with further insight into the sound-producing mechanism
Colleye, Orphal ULg; Ovidio, Michaël ULg; Salmon, André et al

in Frontiers in Zoology (2013), 10(71),

Background: The freshwater sculpins (genus Cottus) are small, bottom-living fishes widely distributed in North America and Europe. The taxonomy of European species has remained unresolved for a long time ... [more ▼]

Background: The freshwater sculpins (genus Cottus) are small, bottom-living fishes widely distributed in North America and Europe. The taxonomy of European species has remained unresolved for a long time due to the overlap of morphological characters. Sound production has already been documented in some cottid representatives, with sounds being involved in courtship and agonistic interactions. Although the movements associated with sound production have been observed, the underlying mechanism remains incomplete. Here, we focus on two closely related species from Belgium: C. rhenanus and C. perifretum. This study aims 1) to record and to compare acoustic communication in both species, 2) to give further insight into the sound-producing mechanism and 3) to look for new morphological traits allowing species differentiation. Results: Both Cottus species produce multiple-pulsed agonistic sounds using a similar acoustic pattern: the first interpulse duration is always longer, making the first pulse unit distinct from the others. Recording sound production and hearing abilities showed a clear relationship between the sound spectra and auditory thresholds in both species: the peak frequencies of calls are around 150 Hz, which corresponds to their best hearing sensitivity. However, it appears that these fishes could not hear acoustic signals produced by conspecifics in their noisy habitat considering their hearing threshold expressed as sound pressure (~ 125 dB re 1 ␣Pa). High-speed video recordings highlighted that each sound is produced during a complete back and forth movement of the pectoral girdle. Conclusions: Both Cottus species use an acoustic pattern that remained conserved during species diversification. Surprisingly, calls do not seem to have a communicative function. On the other hand, fish could detect substrate vibrations resulting from movements carried out during sound production. Similarities in temporal and spectral characteristics also suggest that both species share a common sound-producing mechanism, likely based on pectoral girdle vibrations. From a morphological point of view, only the shape of the spinelike scales covering the body allows species differentiation. [less ▲]

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See detailSound Characteristics and Complex Sonic Apparatus Morphologies in Two Ophidiiformes: Ophidion rochei (Ophidiidae) and Onuxodon fowleri (Carapidae)
Kever, Loïc ULg; Colleye, Orphal ULg; Lecchini, David et al

Conference (2013, July 14)

Ophidiiformes show complex and highly diverse sonic apparatus morphologies allowing them a great variety of calls. Some Ophidion (Ophidiidae) and all Onuxodon (Carapidae) species have in common, at the ... [more ▼]

Ophidiiformes show complex and highly diverse sonic apparatus morphologies allowing them a great variety of calls. Some Ophidion (Ophidiidae) and all Onuxodon (Carapidae) species have in common, at the front of the swimbladder, a mineralized structure called rocker bone. According to morphological observations, it probably results from adaptive convergence. Its evolutionary advantage remains however to be determined. Sonic apparatus morphology and sound characteristics were examined in Ophidion rochei from Dùlce-Glàva (Croatia) and in Onuxodon fowleri from Makemo (French Polynesia). The rocker bone is only present in males in O. rochei but in both sexes in O. fowleri. Onuxodon fowleri and male O. rochei produce calls that often last more than 1 s. Calls are composed of 1 to 41 pulses lasting for 21±10 ms in O. fowleri and 1 to 55 pulses lasting for 16±13 ms in O. rochei. Mean pulse periods are also relatively long, ca. 95 ms and 125 ms, respectively. Females of O. rochei produce short (ca. 20 ms) hum-like sounds that are characterized by shorter pulses (mean duration: 0.7±0.2 ms) and higher pulse rates (mean pulse period: 4±1 ms). Differences in sound characteristics are likely due to the rocker bone that most probably evolved in response to mechanical constraints acting on the swimbladder in O. fowleri and male O. rochei. Its presence suggests a sustained sound production was crucial in their evolutionary success. However, the sexual dimorphism observed in O. rochei but not in O. fowleri suggests differences in way of life. [less ▲]

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See detailOverview on the diversity of sounds produced by clownfishes (Pomacentridae): importance of acoustic signals in their peculiar way of life.
Colleye, Orphal ULg; Parmentier, Eric ULg

in PLoS ONE (2012), 7(11),

Background: Clownfishes (Pomacentridae) are brightly colored coral reef fishes well known for their mutualistic symbiosis with tropical sea anemones. These fishes live in social groups in which there is a ... [more ▼]

Background: Clownfishes (Pomacentridae) are brightly colored coral reef fishes well known for their mutualistic symbiosis with tropical sea anemones. These fishes live in social groups in which there is a size-based dominance hierarchy. In this structure where sex is socially controlled, agonistic interactions are numerous and serve to maintain size differences between individuals adjacent in rank. Clownfishes are also prolific callers whose sounds seem to play an important role in the social hierarchy. Here, we aim to review and to synthesize the diversity of sounds produced by clownfishes in order to emphasize the importance of acoustic signals in their way of life. Methodology/Principal Findings: Recording the different acoustic behaviors indicated that sounds are divided into two main categories: aggressive sounds produced in conjunction with threat postures (charge and chase), and submissive sounds always emitted when fish exhibited head shaking movements (i.e. a submissive posture). Both types of sounds showed size-related intraspecific variation in dominant frequency and pulse duration: smaller individuals produce higher frequency and shorter duration pulses than larger ones, and inversely. Consequently, these sonic features might be useful cues for individual recognition within the group. This observation is of significant importance due to the size-based hierarchy in clownfish group. On the other hand, no acoustic signal was associated with the different reproductive activities. Conclusions/Significance: Unlike other pomacentrids, sounds are not produced for mate attraction in clownfishes but to reach and to defend the competition for breeding status, which explains why constraints are not important enough for promoting call diversification in this group. [less ▲]

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See detailMismatch between shape changes and ecological shifts during the post-settlement growth of the surgeonfish, Acanthurus triostegus
Frederich, Bruno ULg; Colleye, Orphal ULg; Lepoint, Gilles ULg et al

in Frontiers in Zoology (2012), 9

Background: Many coral reef fishes undergo habitat and diet shifts during ontogeny. However, studies focusing on the physiological and morphological adaptations that may prepare them for these transitions ... [more ▼]

Background: Many coral reef fishes undergo habitat and diet shifts during ontogeny. However, studies focusing on the physiological and morphological adaptations that may prepare them for these transitions are relatively scarce. Here, we explored the body shape variation related to ontogenetic shifts in the ecology of the surgeonfish Acanthurus triostegus (Acanthuridae) from new settler to adult stages at Moorea Island (French Polynesia). Specifically, we tested the relationship between diet and habitat shifts and changes in overall body shape during the ontogeny of A. triostegus using a combination of geometric morphometric methods, stomach contents and stable isotope analysis. Results: After reef settlement, stable isotope composition of carbon and nitrogen revealed a change from a zooplanktivorous to a benthic algae diet. The large amount of algae (> 75% of stomach contents) found in the digestive tract of small juveniles (25–30 mm SL) suggested the diet shift is rapid. The post-settlement growth of A. triostegus is highly allometric. The allometric shape changes mainly concern cephalic and pectoral regions. The head becomes shorter and more ventrally oriented during growth. Morphological changes are directly related to the diet shift given that a small mouth ventrally oriented is particularly suited for grazing activities at the adult stage. The pectoral fin is more anteriorely and vertically positioned and its basis is larger in adults than in juveniles. This shape variation had implications for swimming performance, manoeuvrability, turning ability and is related to habitat shift. Acanthurus triostegus achieves its main transformation of body shape to an adult-like form at size of 35–40 mm SL. Conclusion: Most of the shape changes occurred after the reef colonization but before the transition between juvenile habitat (fringing reef) and adult habitat (barrier reef). A large amount of allometric variation was observed after diet shift from zooplankton to benthic algae. Diet shift could act as an environmental factor favouring or inducing morphological changes. On the other hand, the main shape changes have to be achieved before the recruitment to adult populations and start negotiating the biophysical challenges of locomotion and feeding in wave- and current-swept outer reef habitat. [less ▲]

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See detailFurther insight into the sound-producing mechanism of clownfishes: what structure is involved in sound radiation?
Colleye, Orphal ULg; Nakamura, Masaru; Frederich, Bruno ULg et al

in Journal of Experimental Biology (2012), 215

It was recently demonstrated that clownfishes produce aggressive sounds by snapping their jaw teeth. To date, only the onset of the sound has been studied, which raises the question, what structure is ... [more ▼]

It was recently demonstrated that clownfishes produce aggressive sounds by snapping their jaw teeth. To date, only the onset of the sound has been studied, which raises the question, what structure is involved in sound radiation? Here, a combination of different approaches has been used to determine the anatomical structure(s) responsible for the size-related variations observed in sound duration and frequency. Filling the swimbladder with physiological liquid specifically modified size-related acoustic features by inducing a significant decrease in pulse duration of approximately 3 ms and a significant increase in dominant frequency of approximately 105 Hz. However, testing the acoustics of the swimbladder by striking it with a piezoelectric impact hammer showed that this structure is a highly damped sound source prevented from prolonged vibrations. In contrast, the resonant properties of the rib cage seems to account for the size-related variations observed in acoustic features. For an equivalent strike on the rib cage, the duration and dominant frequency of induced sounds changed with fish size: sound duration and dominant frequency were positively and negatively correlated with fish size, respectively. Such relationships between sonic features and fish size are consistent with those observed in natural sounds emitted by fish. Therefore, the swimbladder itself does not act as a resonator; its wall just seems to be driven by the oscillations of the rib cage. This set of observations suggests the need for reassessment of the acoustic role of swimbladders in various fish species. [less ▲]

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See detailImplication of aggressive, submissive and reproductive sounds in the way of life of clownfishes
Colleye, Orphal ULg; Parmentier, Eric ULg

Conference (2012)

Clownfishes are brightly coloured coral reef fishes well known for their mutualistic symbiosis with tropical sea anemones. These fishes live in social groups in which there is a size-based dominance ... [more ▼]

Clownfishes are brightly coloured coral reef fishes well known for their mutualistic symbiosis with tropical sea anemones. These fishes live in social groups in which there is a size-based dominance hierarchy. In this structure where sex is socially controlled, agonistic interactions are numerous and serve to maintain size differences between individuals adjacent in rank. Clownfishes are also prolific callers whose sounds seem to play an important role in the social hierarchy. Agonistic interactions being involved in daily behaviour suggest how important acoustic communication might be in their way of life. Recording the different acoustic behaviours indicated that sounds are divided into two main categories: aggressive sounds produced in conjunction with threat postures (charge and chase), and submissive sounds always emitted when fish exhibited an appeasement display (namely the head shaking movements). Both types of sounds showed size-related intraspecific variation in dominant frequency and pulse duration: smaller individuals produce higher frequency and shorter duration pulses than larger ones. Consequently, these sonic features might be useful cues for individual recognition within the group. On the other hand, no acoustic call was associated with courtship and reproductive behaviours. Unlike other pomacentrids, sounds are not produced for mate attraction in clownfishes but to reach and to defend their breeding status, which explains why constraints are not important enough for promoting call diversification in this genus. However, acoustic signals seem to be an integral part of the peculiar way of life of clownfishes, although they are restricted to agonistic interactions only. [less ▲]

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See detailDiversité du répertoire acoustique des poissons clowns
Colleye, Orphal ULg; Parmentier, Eric ULg

Conference (2012)

Les poissons clowns (Amphiprion spp.) appartiennent à la famille des Pomacentridae. Ces poissons sont bien connus pour leur relation de mutualisme avec les anémones de mer. Au sein de leur hôte, ils ... [more ▼]

Les poissons clowns (Amphiprion spp.) appartiennent à la famille des Pomacentridae. Ces poissons sont bien connus pour leur relation de mutualisme avec les anémones de mer. Au sein de leur hôte, ils vivent en groupe composé d’un nombre variable d’individus selon les espèces. Chaque groupe est hiérarchisée sur la base de la taille des individus : la femelle est l’individu le plus grand et dominant, elle est accompagnée d’un mâle reproducteur, lui même suivi des autres individus sexuellement immatures toujours ordonnés selon leur taille. Cette structure sociale implique le respect de la hiérarchie et de la territorialité. Les interactions agonistiques jouent un rôle important car elles permettent de maintenir des différences de tailles entre les individus de rang adjacent pour éviter les conflits incessants entre individus dominants et subordonnés. Des comportements d’agression sont donc réalisés de la part de chaque dominant envers le ou les subordonnés de rangs inférieurs. En réponse à ces comportements d’agression, les individus subordonnés adoptent des postures d’apaisement envers le ou les dominants de rang supérieur. En plus de ces différents comportements agonistiques, la reproduction est très ritualisée et comporte plusieurs phases telles que la préparation du nid, les parades amoureuses, la ponte ou encore les soins prodigués aux œufs. Quelques études ont rapporté que ces différents comportements agonistiques et reproducteurs pouvaient s’accompagner d’émissions sonores. Cependant, ces études souffraient d’un manque de rigueur dans la description des sons et de leur contexte d’émission. L’intérêt de la présente étude était donc d’identifier et de décrire les sons produits dans divers contextes comportementaux afin de déterminer si différents types de sons peuvent être liés à un même comportement ou encore si un même son peut intervenir dans différents contextes. Les enregistrements de sons indiquent qu’aucun signal acoustique n’est associé aux différentes activités liées à la reproduction. Lors des interactions agonistiques, deux types de sons ont été enregistrés. Les sons d’agression sont toujours émis par un individu dominant à l’encontre d’un subordonné lors des poursuites et autres comportements de menace. A l’inverse, les sons de soumission sont émis par les subordonnés lors d’un comportement caractéristique qualifié de "head shaking". Ces deux types de sons présentent plusieurs différences dans leur allure acoustique et leurs paramètres. Les sons d’agression se composent toujours d’une pulsation qui peut être émise seule ou en série alors que les sons de soumissions sont toujours composés de plusieurs pulsations et sont généralement émis sous forme de train de plusieurs sons. Les durées des pulsations des sons d’agression sont plus longues que celles des sons de soumission. La période des pulsations est considérablement plus longue pour les sons d’agression que pour les sons de soumission, suggérant que chaque pulsation est émise comme une unité bien distincte. De plus, la durée des sons est beaucoup plus longue pour les sons d’agression que pour les sons de soumission. Ces deux types de sons agonistiques montrent également des variations intraspécifiques liées à la taille au niveau de la fréquence dominante et la durée des pulsations. Plus un poisson est grand, plus les sons qu’il émet présente des fréquences basses et des durées élevées, et inversement. Ces différences observées dans les fréquences et les durées des pulsations n’apparaissent ni liées au sexe, ni au rang social mais dépendent uniquement du dimorphisme. Au sein du groupe, les deux types de sons agonistiques semblent donc avoir des fonctions différentes : les sons d’agression pourraient avoir un rôle dissuasif en transmettant un signal de rappel du rang social, alors que les sons de soumission pourraient avoir un rôle d’apaisement en rappelant le statut social du subordonné. Par ailleurs, les fréquences dominantes et les durées des pulsations sont des signaux acoustiques qui véhiculent des informations relatives à la taille de l’individu émetteur ; ils pourraient donc jouer un rôle important dans la reconnaissance de l’individu et le maintien de la cohésion au sein du groupe. [less ▲]

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See detailContribution to the study on sound production in clownfishes (Perciformes, Pomacentridae): a multidisciplinary approach
Colleye, Orphal ULg

Doctoral thesis (2011)

Clownfishes (Amphiprion spp.) are brightly colored fishes that are members of the Pomacentridae family. They are well known for their mutualistic relationship with tropical sea anemones. These fishes live ... [more ▼]

Clownfishes (Amphiprion spp.) are brightly colored fishes that are members of the Pomacentridae family. They are well known for their mutualistic relationship with tropical sea anemones. These fishes live in social groups in which there is a size-based dominance hierarchy. In this structure where sex is socially controlled, agonistic interactions are numerous and serve to maintain size differences between individuals adjacent in rank. Several studies have reported that vocalizations are associated with agonistic interactions but precise data are lacking and further investigations are needed. The nature of the sound-producing mechanisms also remained unresolved, only resting on few assumptions. Thereby, the main aim of the present thesis is (1) to determine the fundamental components of the acoustic communication in clownfishes, and (2) to explain the mechanisms of sound production. In order to achieve these objectives, the research has been divided into three different axes. Firstly, the study of the acoustic behaviors shows that no acoustic signal is associated with reproductive activities in clownfishes. Sound recordings during agonistic interactions indicate that these fishes produce two types of sounds. Aggressive sounds are produced during chases and threat displays while submissive (or head shaking) sounds are emitted in reaction to aggressive acts by dominant. Both types of sounds show size-related intraspecific differences in dominant frequency and pulse duration: smaller individuals produce higher frequency and shorter duration pulses than larger individuals, and inversely. Consequently, these sonic features might be useful cues for individual recognition and maintenance of cohesion within the group. Secondly, the study of the sound-producing mechanism highlights that aggressive sounds are initiated by buccal jaw teeth snapping caused by rapid mouth closure attributed to a sonic ligament. It appears that the swimbladder does not function as a resonator that amplifies and changes the quality of sounds. This structure is a highly damped sound source prevented from prolonged resonant vibrations. On the other hand, the rib cage might be the major acoustic radiator and its resonant properties might explain the size-related variations observed in pulse duration and dominant frequency. Thirdly, the comparison of aggressive sounds among fourteen clownfish species indicates that the same relationship between fish size and both dominant frequency and pulse duration is spread over the entire group (i.e. tribe Amphiprionini). These results highlight all species use a highly conservative mechanism of vocalization. Pulse period appears to be the most variable acoustic feature and could be involved in species-specific recognition, as well as pulse duration and dominant frequency in a lesser extent through their relationship with body size. Although sound production appears to be restricted to some agonistic behaviors, these sounds seem to constitute an integral part of the peculiar way of life of clownfishes. The aggressive and submissive sounds would also result from two different mechanisms.   [less ▲]

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See detailInterspecific variation of calls in clownfishes: degree of similarity in closely related species
Colleye, Orphal ULg; Vandewalle, Pierre ULg; Lanterbecq, Déborah et al

in BMC Evolutionary Biology (2011), 11

Clownfishes are colorful coral reef fishes living in groups in association with sea anemones throughout the Indo-Pacific Ocean. Within their small societies, size hierarchy determines which fish have ... [more ▼]

Clownfishes are colorful coral reef fishes living in groups in association with sea anemones throughout the Indo-Pacific Ocean. Within their small societies, size hierarchy determines which fish have access to reproduction. These fishes are also prolific callers whose aggressive sounds seem to play an important role in the social hierarchy. Agonistic interactions being involved in daily behaviour suggest how acoustic communication might play an important role in clownfish group. Sounds were recorded and compared in fourteen clownfish species (some of which have never been recorded before) to evaluate the potential role of acoustic communication as an evolutionary driving force. Surprisingly, the relationship between fish size and both dominant frequency and pulse duration is not only species-specific; all the specimens of the 14 species are situated on exactly the same slope, which means the size of any Amphiprion can be predicted by both acoustic features. The number of pulses broadly overlaps among species, whereas the pulse period displays the most variation even if it shows overlap among sympatric species. Sound comparisons between three species (A. akallopisos, A. ocellaris and A. frenatus) having different types of teeth and body shape do not show differences neither in the acoustic waveform nor in the power spectrum. Significant overlap in acoustic features demonstrates that the sound-producing mechanism is highly conservative among species. Differences in the calls of some species are due to size dimorphism and the sound variation might be in this case a by-product. This morphological constraint does not permit a consideration of acoustic communication as the main driving force in the diversification of clownfishes. Moreover, calls are not produced to find mate and consequently are less subject to variations due to partner preference, which restricts the constraints of diversification. Calls are produced to reach and defend the competition to mate access. However, differences in the pulse period between cohabiting species show that, in some case, sounds can help to differentiate the species, to prevent competition between cohabiting species and to promote the diversification of taxa. [less ▲]

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See detailAgonistic sounds in the clownfish Amphiprion clarkii: implication of the swimbladder in the sound-producing mechanism
Colleye, Orphal ULg; Nakamura, Masaru; Parmentier, Eric ULg

Poster (2009)

Clownfishes are aggressive fishes that use sound production to defend their anemone territory. It has been shown that they produce agonistic sounds using a jaw teeth snapping. At present, this mechanism ... [more ▼]

Clownfishes are aggressive fishes that use sound production to defend their anemone territory. It has been shown that they produce agonistic sounds using a jaw teeth snapping. At present, this mechanism has highlighted the onset of the sound but has not explained yet which structure is responsible for the sound modulation. Interestingly, some acoustic features such as dominant frequency and pulse duration are directly related to fish size. Such variations are linked to a morphological constraint. Also, the existent relationship between fish size and swimbladder size implies that the swimbladder might be involved in the sound production. Sound analyses in Amphiprion clarkii showed that the experimental filling of the swimbladder with physiological liquid (NaCl 9‰) significantly modified the acoustic features. The most striking changes were a significant increase in dominant frequency and a significant decrease in pulse duration. These observations highlighted the implication of the swimbladder in sound modulation. In clownfishes, dominant frequency and pulse duration are morphologically determined signals. The swimbladder appears to modulate these acoustic features by acting as a resonant chamber. [less ▲]

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See detailHearing ability in three clownfish species
Parmentier, Eric ULg; Colleye, Orphal ULg; Mann, David

in Journal of Experimental Biology (2009), 212

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See detailHistological study of the sex-change in the skunk clownfish Amphiprion akallopisos
Casadevall, Margarida; Delgado, E.; Colleye, Orphal ULg et al

in The Open Fish Science Journal (2009), 2

Sex change in the protandrous fish Amphiprion akallopisos Bleeker, 1853 (F.Pomacentridae) has been analysed. Experiments consisted of placing males together after being separated from their mates, and ... [more ▼]

Sex change in the protandrous fish Amphiprion akallopisos Bleeker, 1853 (F.Pomacentridae) has been analysed. Experiments consisted of placing males together after being separated from their mates, and observe changes in gonad histology at different periods, in order to identify signs of the sex change process. The presence of a first invagination on the male gonad wall, and the observation of the first cortical alveoli oocytes as an indication of the beginning of the vitellogenesis process, was the first symptom of the sex change, which has been detected after 18 days in one of the males. Period needed for the sex changing process was size independent. The process by which wall invagination is converted into ovarian lumen in the future mature ovary is also described. [less ▲]

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See detail15th Benelux Congress of Zoology abstract book
Colleye, Orphal ULg; Dauby, Patrick ULg; Fabri, Gregory et al

Book published by Editions de l'université de Liège (2008)

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See detailAgonistic sounds in the skunk clownfish (Amphiprion akallopisos) : spectral and temporal basis for fish size assessment and individual recognition
Colleye, Orphal ULg; Frederich, Bruno ULg; Vandewalle, Pierre ULg et al

Poster (2008)

Clownfishes (i.e. Amphiprion akallopisos) are territorial fishes that use sound production to defend their anemone territory. They live in social groups within which there is a size-based dominance ... [more ▼]

Clownfishes (i.e. Amphiprion akallopisos) are territorial fishes that use sound production to defend their anemone territory. They live in social groups within which there is a size-based dominance hierarchy. In such a system, agonistic interactions are usual and play an important role in social organization by maintaining size differences between individuals adjacent in rank. Sounds are known to be used in agonistic interactions; they could therefore be associated with aggressive display within the group hierarchy. In the present study, we compared the sonic characteristics between individuals of different sizes and of different sexual status (non-breeder, male and female). Sound analysis revealed that dominant frequency and pulse length are highly correlated with fish size, and are not related to sex. No information related to size can be extracted from the pulse period, interpulse duration and number of pulses per train. Evidence is provided that dominant frequency and pulse length are morphologically determined signals related to fish size. In that case, smaller individuals produce shorter duration and higher frequency sounds than larger individuals. Both sonic features are signals conveying information related to the size of the emitter. This finding could be of significant importance, and might help to understand one of the mechanisms that carry the clue for individual recognition within the group hierarchy. [less ▲]

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See detailEffects of fish size on agonistic sounds in the clownfish Amphiprion akallopisos : implications for the role of the swimbladder in the sound production mechanism?
Colleye, Orphal ULg; Vandewalle, Pierre ULg; Frederich, Bruno ULg et al

Conference (2008)

Clownfishes (i.e. Amphiprion akallopisos) are territorial fishes that use sound production to defend their anemone territory. They live in social groups which display a size-based dominance hierarchy. In ... [more ▼]

Clownfishes (i.e. Amphiprion akallopisos) are territorial fishes that use sound production to defend their anemone territory. They live in social groups which display a size-based dominance hierarchy. In such a system, agonistic interactions are frequent and play an important role in the social organization. In addition, these interactions are often associated with sounds. In this study, we compared the sonic features between individuals of different sizes and in different sexual status (juvenile, male and female). The existent relationship between fish size and swimbladder size also implied to seek the swimbladder role in the sound production. Sound analyses showed that juveniles, males and females had distinct sounds in the dominant frequency and pulse duration. These differences were however not in relation to the sexual state; influence of sex on sonic features being mainly the result of a size dimorphism between sexes. Differences in calls were therefore due to the respective size of the emitter. This observation highlighted the role of the swimbladder as a resonance chamber. This role was also reinforced because the experimental filling of the swimbladder with physiological liquid significantly modified the acoustic features. In A. akallopisos, frequency and pulse duration are directly related to swimbladder size, and thus to fish size. This relationship provides strong evidence that the emitter could be identified by its calls. [less ▲]

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See detailSound production in the clownfish Amphiprion clarkii
Parmentier, Eric ULg; Colleye, Orphal ULg; Fine, M. L. et al

in Science (2007), 316(5827), 1006-1006

Although clownfish sounds were recorded as early as 1930, the mechanism of sound production has remained obscure. Yet, clownfish are prolific "singers" that produce a wide variety of sounds, described as ... [more ▼]

Although clownfish sounds were recorded as early as 1930, the mechanism of sound production has remained obscure. Yet, clownfish are prolific "singers" that produce a wide variety of sounds, described as "chirps" and "pops" in both reproductive and agonistic behavioral contexts. Here, we describe the sonic mechanism of the clownfish Amphiprion clarkii. [less ▲]

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